Semiconductor magnetic field sensors have been disclosed in the prior art. See. e.g., European Patent No. 0148 330 A2. In this particular reference, a Hall element is disclosed having first and second contact zones which are both made of a semiconductor material of conductivity type P. These zones are located on an outer surface of a semiconductor material of another conductivity type N and are provided with a sensor connection S1 or S2. An insulating layer is provided on the outer surface of the semiconductor material of conductivity type N with passages for the sensor connections S1 and S2.
In the operation of Hall-effect components, the electrical current flow is known to result from charged-carrier drift or of charged-carrier diffusion. This form of charge transport depends on the properties of the semiconductor used and on the environmental conditions. Any change in the semiconductor properties or the environment causes a change in the output signal of the Hall-effect component. Hall-effect components are particularly sensitive to surface effects, encapsulation stress, light, temperature, changes in the material doping density, etc. Therefore, to obtain high-precision magnetic field sensors, the Hall effect component must be made of a special semiconductor material, including a special encapsulation, and by means of non-standard process steps. Furthermore, external temperature variations must be compensated for. For this reason, it is difficult to integrate a good Hall-effect component into a signal processing circuit.
An object of the present invention is to provide a magnetic field sensor which is capable of measuring magnetic fields with high precision. An additional object of the present invention is to provide a high precision magnetic field sensor which can be manufactured using conventional standard integrated circuit MOS technology and which can be integrated without additional process steps into a complex conventional MOS circuit. It is a further object of the present invention to provide a magnetic sensor capable of producing an output signal which is relatively independent of the properties of the semiconductor material and of environmental conditions.